Ethanol Gas And UV Sensors Based On ZnO Microwire

Zinc Oxide (ZnO), belonging to the third-generation semiconductor, is an ideal material for fabricating optoelectronic devices, owing to its wide band gap of3.37eV and the exciton binding energy as high as60meV. ZnO is a kind of Ⅱb-VIcompound semiconductors and has many other advantages, such as good chemical and thermal stability, piezoelectricity, low toxicity, good biocompatibility and high electron mobility, all of which make it a research hotspot in the field of semiconductor. ZnO also has colorful micro/nanostructures which have especially large specific surface area and quantum confinement effect, so that it has great potential applications in the field of micro/nano devices.hi this study, we report a ZnO-based ethanol gas sensor and a ZnO-based UV sensor, in which one-dimensional (1D) ZnO microwires are used as their core part. The main research contents and results are as follows:1. Fabricating ZnO microwire based ethanol gas sensors and discussing their sensing properties. Firstly, ZnO microwires were synthesized successfully by chemical vapor deposition (CVD). Secondly, a single ZnO microwire was fixed on a base board with silver paste to form a probe type ethanol gas sensor. Thirdly, a home-built sealed plastic chamber was used to study the sensing property. By discussing the sensitivity, repeatability and detect limit of the as-prepared sensor, we explain the corresponding detection mechanism:The C2H5OH gas played as a reductive gas not a oxidative gas in our experiment, which is opposite to the mechanism described in the most literatures. Therefore, it is necessary to make the sensor work under the illumination including UV component for keeping a relative lower resistance of ZnO microwire. In our research, we find that the sensitivity of the device remained unchanged when parallelly connecting several single-wire devices (1-WD) into a multi-wire device (m-WD), however, its reliability and stability can be efficiently improved by using this simple method. This sensor has a unique advantage:it can sensitively detect ethanol gas at room temperature (RT) without an extra heating element.2. Discussing the UV sensitivity of ZnO microwire and designing a kind of sphere array structure, which has good performance of locating and velocity measurement to the target in theory and can be used as the core part of the UV warning system.